The use of electrical contactors or other power control means that operate in a similar manner, as generally represented by reference numeral 10 in FIG. 1, for powering electrical equipment is well known. The contactor 10 includes a power contact 14, having one or more sets of two fixed power contacts 18, one being the input contact connected to a power source and the other being the output or load contact connected to equipment that will receive power from the power source. The contactor 10 also includes a set of two movable power contacts 22, electrically connected by a bridge 26, for each set of fixed power contacts 18. The fixed power contacts 18 are generally secured to a structural component of the contactor 10 such that they do not move. The bridge 26 of movable power contacts 22 is mounted in a window 30 defined in a contact carrier 34. The bridge 26 is biased against a generally flat support surface 38 of the window 30 by means such as a spring 42. The support surface 38 is generally perpendicular to the longitudinal axis of the contact carrier 34. The contact carrier 34 is normally biased by means, such as a spring (not shown), to a positon in which the movable power contacts 22 are not in electrical contact with the fixed power contacts 18. In this position the bridge 26 of the movable power contacts 22 is biased against the support surface 38 of window 30 by bridge biasing spring 42. An operating end 46 of the contact carrier 34 is attached to an armature 50 of an electromagnet 54. When power is applied to the electromagnet 54 the armature 50 is drawn into contact with the electromagnet 54. This movement of the armature 50 pulls the attached contact carrier 34 toward the electromagnet 54 causing the movable power contacts 22 to engage the fixed power contacts 18, thereby connecting the power source to any equipment connected to the output of the contactor 10. The movable power contacts 22 engage the fixed power contacts 18 before the armature 50 has fully engaged the electromagnet 54. The bridge biasing spring 42 permits a displacement of the bridge 26 away from the support surface 38 in the window 30 as the armature 50 continues moving toward the electromagnet 54. Therefore, the magnetic attraction between the armature 50 and electromagnet 54 must be stronger than the contact carrier biasing means and the bridge biasing spring 42 to overcome their combined force and close the power contacts 18 and 22, and then to maintain a positive closed position between power contacts 18 and 22. The displacement of the bridge 26 compresses the biasing spring 42 against the bridge 26 and ensures that a positive connection is maintained between the movable power contacts 22 and fixed power contacts 18. This displacement of the bridge 26 within the window 30 and the increased pressure of the bridge biasing spring 42 against the bridge 26 cannot prevent wear of the power contacts 18 and 22, but it can compensate for some of the eventual contact wear.
When power to the electromagnet 54 is terminated the contact carrier biasing means moves the contact carrier 34 away from the electromagnet 54, thereby separating the movable power contacts 22 from the fixed power contacts 18. Since the contact carrier biasing means does not exert as much force as the magnetic attraction of the electromagnet 54 the movable power contacts 22 will not separate from the fixed power contacts 22 as fast as they close on them. Therefore, the power contact 18 and 22 will open a little slower and be subjected to more arcing than during closing. Arcing is a major contributor to wear of the power contacts 18 and 22. As the power contacts 18 and 22 wear, the gap between them increases and their surfaces become more irregular forming more arcing points, which speed up contact wear. Therefore, periodic preventive maintenance should include inspection of the power contacts 18 and 22. If preventive maintenance is not done and the power contacts 18 and 22 fail, unscheduled down time will be required to replace the power contacts 18 and 22 and repair any damage to equipment connected to the contactor 10 and/or products being manufactured by the equipment. Contactor manufacturers generally provide some method or guidelines for inspecting the condition of their power contacts 18 and 22 to determine if they are worn to a point where they require replacement. Normally this contact inspection requires that the contactor 10 be taken off line and partially disassembled to permit a visual inspection of the power contacts 18 and 22. This requires down time of the equipment in which the contactor 10 is installed, any machinery that receives power form the contactor 10, any equipment that might require operation of the equipment connected the contactor 10 that is being inspected and time for a maintenance person to perform the inspection. Since so much down time is consumed doing the periodic inspection the power contacts 14 are usually replaced regardless of their wear condition, which adds to the down time cost. Therefore, it would be desirable to have a continuously running contact evaluation system that learns the initial configuration of the power contacts 18 and 22, can provide current condition information about the power contacts 18 and 22, continuously or in response to a request, and provide a notification of required maintenance when power contacts 18 and 22 have reached a predetermined level of wear (wear limit) without the need of shutting equipment down for a periodic human inspection of power contacts 18 and 22.